Display screen for a computer



FIG. 1 is a front view of a display screen for a computer, the broken line drawings of a computer display and the circular elements are for illustrative purposes only and forms no part of the claimed design; and,

FIG. 2 is a front view of a second embodiment thereof, the broken line drawings of a computer display and circular elements are for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a display screen for a computer, as shown and described. 